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b57aee66 PM |
1 | /* |
2 | * urcu-call-rcu.c | |
3 | * | |
4 | * Userspace RCU library - batch memory reclamation with kernel API | |
5 | * | |
6 | * Copyright (c) 2010 Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
7 | * | |
8 | * This library is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with this library; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
23 | #include <stdio.h> | |
24 | #include <pthread.h> | |
25 | #include <signal.h> | |
26 | #include <assert.h> | |
27 | #include <stdlib.h> | |
28 | #include <string.h> | |
29 | #include <errno.h> | |
30 | #include <poll.h> | |
31 | #include <sys/time.h> | |
32 | #include <syscall.h> | |
33 | #include <unistd.h> | |
34 | ||
35 | #include "config.h" | |
36 | #include "urcu/wfqueue.h" | |
37 | #include "urcu-call-rcu.h" | |
38 | #include "urcu-pointer.h" | |
3c24913f | 39 | #include "urcu/list.h" |
b57aee66 PM |
40 | |
41 | /* Data structure that identifies a call_rcu thread. */ | |
42 | ||
43 | struct call_rcu_data { | |
44 | struct cds_wfq_queue cbs; | |
45 | unsigned long flags; | |
46 | pthread_mutex_t mtx; | |
47 | pthread_cond_t cond; | |
48 | unsigned long qlen; | |
49 | pthread_t tid; | |
3c24913f | 50 | struct cds_list_head list; |
b57aee66 PM |
51 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
52 | ||
3c24913f PM |
53 | /* |
54 | * List of all call_rcu_data structures to keep valgrind happy. | |
55 | * Protected by call_rcu_mutex. | |
56 | */ | |
57 | ||
58 | CDS_LIST_HEAD(call_rcu_data_list); | |
59 | ||
b57aee66 PM |
60 | /* Link a thread using call_rcu() to its call_rcu thread. */ |
61 | ||
62 | static __thread struct call_rcu_data *thread_call_rcu_data; | |
63 | ||
64 | /* Guard call_rcu thread creation. */ | |
65 | ||
66 | static pthread_mutex_t call_rcu_mutex = PTHREAD_MUTEX_INITIALIZER; | |
67 | ||
68 | /* If a given thread does not have its own call_rcu thread, this is default. */ | |
69 | ||
70 | static struct call_rcu_data *default_call_rcu_data; | |
71 | ||
b57aee66 PM |
72 | /* |
73 | * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are | |
74 | * available, then we can have call_rcu threads assigned to individual | |
75 | * CPUs rather than only to specific threads. | |
76 | */ | |
77 | ||
78 | #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) | |
79 | ||
80 | /* | |
81 | * Pointer to array of pointers to per-CPU call_rcu_data structures | |
82 | * and # CPUs. | |
83 | */ | |
84 | ||
85 | static struct call_rcu_data **per_cpu_call_rcu_data; | |
86 | static long maxcpus; | |
87 | ||
88 | /* Allocate the array if it has not already been allocated. */ | |
89 | ||
90 | static void alloc_cpu_call_rcu_data(void) | |
91 | { | |
92 | struct call_rcu_data **p; | |
93 | static int warned = 0; | |
94 | ||
95 | if (maxcpus != 0) | |
96 | return; | |
97 | maxcpus = sysconf(_SC_NPROCESSORS_CONF); | |
98 | if (maxcpus <= 0) { | |
99 | return; | |
100 | } | |
101 | p = malloc(maxcpus * sizeof(*per_cpu_call_rcu_data)); | |
102 | if (p != NULL) { | |
103 | memset(p, '\0', maxcpus * sizeof(*per_cpu_call_rcu_data)); | |
104 | per_cpu_call_rcu_data = p; | |
105 | } else { | |
106 | if (!warned) { | |
107 | fprintf(stderr, "[error] liburcu: unable to allocate per-CPU pointer array\n"); | |
108 | } | |
109 | warned = 1; | |
110 | } | |
111 | } | |
112 | ||
113 | #else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */ | |
114 | ||
115 | static const struct call_rcu_data **per_cpu_call_rcu_data = NULL; | |
116 | static const long maxcpus = -1; | |
117 | ||
118 | static void alloc_cpu_call_rcu_data(void) | |
119 | { | |
120 | } | |
121 | ||
122 | static int sched_getcpu(void) | |
123 | { | |
124 | return -1; | |
125 | } | |
126 | ||
127 | #endif /* #else #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */ | |
128 | ||
129 | /* Acquire the specified pthread mutex. */ | |
130 | ||
131 | static void call_rcu_lock(pthread_mutex_t *pmp) | |
132 | { | |
133 | if (pthread_mutex_lock(pmp) != 0) { | |
134 | perror("pthread_mutex_lock"); | |
135 | exit(-1); | |
136 | } | |
137 | } | |
138 | ||
139 | /* Release the specified pthread mutex. */ | |
140 | ||
141 | static void call_rcu_unlock(pthread_mutex_t *pmp) | |
142 | { | |
143 | if (pthread_mutex_unlock(pmp) != 0) { | |
144 | perror("pthread_mutex_unlock"); | |
145 | exit(-1); | |
146 | } | |
147 | } | |
148 | ||
149 | /* This is the code run by each call_rcu thread. */ | |
150 | ||
151 | static void *call_rcu_thread(void *arg) | |
152 | { | |
153 | unsigned long cbcount; | |
154 | struct cds_wfq_node *cbs; | |
155 | struct cds_wfq_node **cbs_tail; | |
156 | struct call_rcu_data *crdp = (struct call_rcu_data *)arg; | |
157 | struct rcu_head *rhp; | |
158 | ||
159 | thread_call_rcu_data = crdp; | |
160 | for (;;) { | |
161 | if (&crdp->cbs.head != _CMM_LOAD_SHARED(crdp->cbs.tail)) { | |
162 | while ((cbs = _CMM_LOAD_SHARED(crdp->cbs.head)) == NULL) | |
163 | poll(NULL, 0, 1); | |
164 | _CMM_STORE_SHARED(crdp->cbs.head, NULL); | |
165 | cbs_tail = (struct cds_wfq_node **) | |
166 | uatomic_xchg(&crdp->cbs.tail, &crdp->cbs.head); | |
167 | synchronize_rcu(); | |
168 | cbcount = 0; | |
169 | do { | |
170 | while (cbs->next == NULL && | |
171 | &cbs->next != cbs_tail) | |
172 | poll(NULL, 0, 1); | |
173 | if (cbs == &crdp->cbs.dummy) { | |
174 | cbs = cbs->next; | |
175 | continue; | |
176 | } | |
177 | rhp = (struct rcu_head *)cbs; | |
178 | cbs = cbs->next; | |
179 | rhp->func(rhp); | |
180 | cbcount++; | |
181 | } while (cbs != NULL); | |
182 | uatomic_sub(&crdp->qlen, cbcount); | |
183 | } | |
7106ddf8 PM |
184 | if (crdp->flags & URCU_CALL_RCU_STOP) |
185 | break; | |
b57aee66 PM |
186 | if (crdp->flags & URCU_CALL_RCU_RT) |
187 | poll(NULL, 0, 10); | |
188 | else { | |
189 | call_rcu_lock(&crdp->mtx); | |
190 | _CMM_STORE_SHARED(crdp->flags, | |
191 | crdp->flags & ~URCU_CALL_RCU_RUNNING); | |
192 | if (&crdp->cbs.head == | |
193 | _CMM_LOAD_SHARED(crdp->cbs.tail) && | |
194 | pthread_cond_wait(&crdp->cond, &crdp->mtx) != 0) { | |
195 | perror("pthread_cond_wait"); | |
196 | exit(-1); | |
197 | } | |
198 | _CMM_STORE_SHARED(crdp->flags, | |
199 | crdp->flags | URCU_CALL_RCU_RUNNING); | |
200 | poll(NULL, 0, 10); | |
201 | call_rcu_unlock(&crdp->mtx); | |
202 | } | |
203 | } | |
7106ddf8 PM |
204 | call_rcu_lock(&crdp->mtx); |
205 | crdp->flags |= URCU_CALL_RCU_STOPPED; | |
206 | call_rcu_unlock(&crdp->mtx); | |
207 | return NULL; | |
b57aee66 PM |
208 | } |
209 | ||
210 | /* | |
211 | * Create both a call_rcu thread and the corresponding call_rcu_data | |
3c24913f PM |
212 | * structure, linking the structure in as specified. Caller must hold |
213 | * call_rcu_mutex. | |
b57aee66 PM |
214 | */ |
215 | ||
3c24913f PM |
216 | static void call_rcu_data_init(struct call_rcu_data **crdpp, |
217 | unsigned long flags) | |
b57aee66 PM |
218 | { |
219 | struct call_rcu_data *crdp; | |
220 | ||
221 | crdp = malloc(sizeof(*crdp)); | |
222 | if (crdp == NULL) { | |
223 | fprintf(stderr, "Out of memory.\n"); | |
224 | exit(-1); | |
225 | } | |
226 | memset(crdp, '\0', sizeof(*crdp)); | |
227 | cds_wfq_init(&crdp->cbs); | |
228 | crdp->qlen = 0; | |
229 | if (pthread_mutex_init(&crdp->mtx, NULL) != 0) { | |
230 | perror("pthread_mutex_init"); | |
231 | exit(-1); | |
232 | } | |
233 | if (pthread_cond_init(&crdp->cond, NULL) != 0) { | |
234 | perror("pthread_cond_init"); | |
235 | exit(-1); | |
236 | } | |
237 | crdp->flags = flags | URCU_CALL_RCU_RUNNING; | |
3c24913f | 238 | cds_list_add(&crdp->list, &call_rcu_data_list); |
b57aee66 PM |
239 | cmm_smp_mb(); /* Structure initialized before pointer is planted. */ |
240 | *crdpp = crdp; | |
241 | if (pthread_create(&crdp->tid, NULL, call_rcu_thread, crdp) != 0) { | |
242 | perror("pthread_create"); | |
243 | exit(-1); | |
244 | } | |
245 | } | |
246 | ||
247 | /* | |
248 | * Return a pointer to the call_rcu_data structure for the specified | |
249 | * CPU, returning NULL if there is none. We cannot automatically | |
250 | * created it because the platform we are running on might not define | |
251 | * sched_getcpu(). | |
252 | */ | |
253 | ||
254 | struct call_rcu_data *get_cpu_call_rcu_data(int cpu) | |
255 | { | |
256 | static int warned = 0; | |
257 | ||
258 | if (per_cpu_call_rcu_data == NULL) | |
259 | return NULL; | |
260 | if (!warned && maxcpus > 0 && (cpu < 0 || maxcpus <= cpu)) { | |
261 | fprintf(stderr, "[error] liburcu: get CPU # out of range\n"); | |
262 | warned = 1; | |
263 | } | |
264 | if (cpu < 0 || maxcpus <= cpu) | |
265 | return NULL; | |
266 | return per_cpu_call_rcu_data[cpu]; | |
267 | } | |
268 | ||
269 | /* | |
270 | * Return the tid corresponding to the call_rcu thread whose | |
271 | * call_rcu_data structure is specified. | |
272 | */ | |
273 | ||
274 | pthread_t get_call_rcu_thread(struct call_rcu_data *crdp) | |
275 | { | |
276 | return crdp->tid; | |
277 | } | |
278 | ||
279 | /* | |
280 | * Create a call_rcu_data structure (with thread) and return a pointer. | |
281 | */ | |
282 | ||
3c24913f | 283 | static struct call_rcu_data *__create_call_rcu_data(unsigned long flags) |
b57aee66 PM |
284 | { |
285 | struct call_rcu_data *crdp; | |
286 | ||
287 | call_rcu_data_init(&crdp, flags); | |
288 | return crdp; | |
289 | } | |
290 | ||
3c24913f PM |
291 | struct call_rcu_data *create_call_rcu_data(unsigned long flags) |
292 | { | |
293 | struct call_rcu_data *crdp; | |
294 | ||
295 | call_rcu_lock(&call_rcu_mutex); | |
296 | crdp = __create_call_rcu_data(flags); | |
297 | call_rcu_unlock(&call_rcu_mutex); | |
298 | return crdp; | |
299 | } | |
300 | ||
b57aee66 PM |
301 | /* |
302 | * Set the specified CPU to use the specified call_rcu_data structure. | |
7106ddf8 PM |
303 | * |
304 | * Use NULL to remove a CPU's call_rcu_data structure, but it is | |
305 | * the caller's responsibility to dispose of the removed structure. | |
306 | * Use get_cpu_call_rcu_data() to obtain a pointer to the old structure | |
307 | * (prior to NULLing it out, of course). | |
b57aee66 PM |
308 | */ |
309 | ||
310 | int set_cpu_call_rcu_data(int cpu, struct call_rcu_data *crdp) | |
311 | { | |
312 | int warned = 0; | |
313 | ||
314 | call_rcu_lock(&call_rcu_mutex); | |
315 | if (cpu < 0 || maxcpus <= cpu) { | |
316 | if (!warned) { | |
317 | fprintf(stderr, "[error] liburcu: set CPU # out of range\n"); | |
318 | warned = 1; | |
319 | } | |
320 | call_rcu_unlock(&call_rcu_mutex); | |
321 | errno = EINVAL; | |
322 | return -EINVAL; | |
323 | } | |
324 | alloc_cpu_call_rcu_data(); | |
325 | call_rcu_unlock(&call_rcu_mutex); | |
326 | if (per_cpu_call_rcu_data == NULL) { | |
327 | errno = ENOMEM; | |
328 | return -ENOMEM; | |
329 | } | |
330 | per_cpu_call_rcu_data[cpu] = crdp; | |
331 | return 0; | |
332 | } | |
333 | ||
334 | /* | |
335 | * Return a pointer to the default call_rcu_data structure, creating | |
336 | * one if need be. Because we never free call_rcu_data structures, | |
337 | * we don't need to be in an RCU read-side critical section. | |
338 | */ | |
339 | ||
340 | struct call_rcu_data *get_default_call_rcu_data(void) | |
341 | { | |
342 | if (default_call_rcu_data != NULL) | |
343 | return rcu_dereference(default_call_rcu_data); | |
344 | call_rcu_lock(&call_rcu_mutex); | |
345 | if (default_call_rcu_data != NULL) { | |
346 | call_rcu_unlock(&call_rcu_mutex); | |
347 | return default_call_rcu_data; | |
348 | } | |
349 | call_rcu_data_init(&default_call_rcu_data, 0); | |
350 | call_rcu_unlock(&call_rcu_mutex); | |
351 | return default_call_rcu_data; | |
352 | } | |
353 | ||
354 | /* | |
355 | * Return the call_rcu_data structure that applies to the currently | |
356 | * running thread. Any call_rcu_data structure assigned specifically | |
357 | * to this thread has first priority, followed by any call_rcu_data | |
358 | * structure assigned to the CPU on which the thread is running, | |
359 | * followed by the default call_rcu_data structure. If there is not | |
360 | * yet a default call_rcu_data structure, one will be created. | |
361 | */ | |
362 | struct call_rcu_data *get_call_rcu_data(void) | |
363 | { | |
364 | int curcpu; | |
365 | static int warned = 0; | |
366 | ||
367 | if (thread_call_rcu_data != NULL) | |
368 | return thread_call_rcu_data; | |
369 | if (maxcpus <= 0) | |
370 | return get_default_call_rcu_data(); | |
371 | curcpu = sched_getcpu(); | |
372 | if (!warned && (curcpu < 0 || maxcpus <= curcpu)) { | |
373 | fprintf(stderr, "[error] liburcu: gcrd CPU # out of range\n"); | |
374 | warned = 1; | |
375 | } | |
376 | if (curcpu >= 0 && maxcpus > curcpu && | |
377 | per_cpu_call_rcu_data != NULL && | |
378 | per_cpu_call_rcu_data[curcpu] != NULL) | |
379 | return per_cpu_call_rcu_data[curcpu]; | |
380 | return get_default_call_rcu_data(); | |
381 | } | |
382 | ||
383 | /* | |
384 | * Return a pointer to this task's call_rcu_data if there is one. | |
385 | */ | |
386 | ||
387 | struct call_rcu_data *get_thread_call_rcu_data(void) | |
388 | { | |
389 | return thread_call_rcu_data; | |
390 | } | |
391 | ||
392 | /* | |
393 | * Set this task's call_rcu_data structure as specified, regardless | |
394 | * of whether or not this task already had one. (This allows switching | |
395 | * to and from real-time call_rcu threads, for example.) | |
7106ddf8 PM |
396 | * |
397 | * Use NULL to remove a thread's call_rcu_data structure, but it is | |
398 | * the caller's responsibility to dispose of the removed structure. | |
399 | * Use get_thread_call_rcu_data() to obtain a pointer to the old structure | |
400 | * (prior to NULLing it out, of course). | |
b57aee66 PM |
401 | */ |
402 | ||
403 | void set_thread_call_rcu_data(struct call_rcu_data *crdp) | |
404 | { | |
405 | thread_call_rcu_data = crdp; | |
406 | } | |
407 | ||
408 | /* | |
409 | * Create a separate call_rcu thread for each CPU. This does not | |
410 | * replace a pre-existing call_rcu thread -- use the set_cpu_call_rcu_data() | |
411 | * function if you want that behavior. | |
412 | */ | |
413 | ||
414 | int create_all_cpu_call_rcu_data(unsigned long flags) | |
415 | { | |
416 | int i; | |
417 | struct call_rcu_data *crdp; | |
418 | int ret; | |
419 | ||
420 | call_rcu_lock(&call_rcu_mutex); | |
421 | alloc_cpu_call_rcu_data(); | |
422 | call_rcu_unlock(&call_rcu_mutex); | |
423 | if (maxcpus <= 0) { | |
424 | errno = EINVAL; | |
425 | return -EINVAL; | |
426 | } | |
427 | if (per_cpu_call_rcu_data == NULL) { | |
428 | errno = ENOMEM; | |
429 | return -ENOMEM; | |
430 | } | |
431 | for (i = 0; i < maxcpus; i++) { | |
432 | call_rcu_lock(&call_rcu_mutex); | |
433 | if (get_cpu_call_rcu_data(i)) { | |
434 | call_rcu_unlock(&call_rcu_mutex); | |
435 | continue; | |
436 | } | |
3c24913f | 437 | crdp = __create_call_rcu_data(flags); |
b57aee66 PM |
438 | if (crdp == NULL) { |
439 | call_rcu_unlock(&call_rcu_mutex); | |
440 | errno = ENOMEM; | |
441 | return -ENOMEM; | |
442 | } | |
443 | call_rcu_unlock(&call_rcu_mutex); | |
444 | if ((ret = set_cpu_call_rcu_data(i, crdp)) != 0) { | |
445 | /* FIXME: Leaks crdp for now. */ | |
446 | return ret; /* Can happen on race. */ | |
447 | } | |
448 | } | |
449 | return 0; | |
450 | } | |
451 | ||
7106ddf8 PM |
452 | /* |
453 | * Wake up the call_rcu thread corresponding to the specified | |
454 | * call_rcu_data structure. | |
455 | */ | |
456 | static void wake_call_rcu_thread(struct call_rcu_data *crdp) | |
457 | { | |
458 | if (!(_CMM_LOAD_SHARED(crdp->flags) & URCU_CALL_RCU_RT)) { | |
459 | call_rcu_lock(&crdp->mtx); | |
460 | if (!(_CMM_LOAD_SHARED(crdp->flags) & URCU_CALL_RCU_RUNNING)) { | |
461 | if (pthread_cond_signal(&crdp->cond) != 0) { | |
462 | perror("pthread_cond_signal"); | |
463 | exit(-1); | |
464 | } | |
465 | } | |
466 | call_rcu_unlock(&crdp->mtx); | |
467 | } | |
468 | } | |
469 | ||
b57aee66 PM |
470 | /* |
471 | * Schedule a function to be invoked after a following grace period. | |
472 | * This is the only function that must be called -- the others are | |
473 | * only present to allow applications to tune their use of RCU for | |
474 | * maximum performance. | |
475 | * | |
476 | * Note that unless a call_rcu thread has not already been created, | |
477 | * the first invocation of call_rcu() will create one. So, if you | |
478 | * need the first invocation of call_rcu() to be fast, make sure | |
479 | * to create a call_rcu thread first. One way to accomplish this is | |
480 | * "get_call_rcu_data();", and another is create_all_cpu_call_rcu_data(). | |
481 | */ | |
482 | ||
483 | void call_rcu(struct rcu_head *head, | |
484 | void (*func)(struct rcu_head *head)) | |
485 | { | |
486 | struct call_rcu_data *crdp; | |
487 | ||
488 | cds_wfq_node_init(&head->next); | |
489 | head->func = func; | |
490 | crdp = get_call_rcu_data(); | |
491 | cds_wfq_enqueue(&crdp->cbs, &head->next); | |
492 | uatomic_inc(&crdp->qlen); | |
7106ddf8 PM |
493 | wake_call_rcu_thread(crdp); |
494 | } | |
495 | ||
496 | /* | |
497 | * Free up the specified call_rcu_data structure, terminating the | |
498 | * associated call_rcu thread. The caller must have previously | |
499 | * removed the call_rcu_data structure from per-thread or per-CPU | |
500 | * usage. For example, set_cpu_call_rcu_data(cpu, NULL) for per-CPU | |
501 | * call_rcu_data structures or set_thread_call_rcu_data(NULL) for | |
502 | * per-thread call_rcu_data structures. | |
503 | * | |
504 | * We silently refuse to free up the default call_rcu_data structure | |
505 | * because that is where we put any leftover callbacks. Note that | |
506 | * the possibility of self-spawning callbacks makes it impossible | |
507 | * to execute all the callbacks in finite time without putting any | |
508 | * newly spawned callbacks somewhere else. The "somewhere else" of | |
509 | * last resort is the default call_rcu_data structure. | |
510 | * | |
511 | * We also silently refuse to free NULL pointers. This simplifies | |
512 | * the calling code. | |
513 | */ | |
514 | void call_rcu_data_free(struct call_rcu_data *crdp) | |
515 | { | |
516 | struct cds_wfq_node *cbs; | |
517 | struct cds_wfq_node **cbs_tail; | |
518 | struct cds_wfq_node **cbs_endprev; | |
519 | ||
520 | if (crdp == NULL || crdp == default_call_rcu_data) { | |
521 | return; | |
522 | } | |
523 | if ((crdp->flags & URCU_CALL_RCU_STOPPED) == 0) { | |
b57aee66 | 524 | call_rcu_lock(&crdp->mtx); |
7106ddf8 | 525 | crdp->flags |= URCU_CALL_RCU_STOP; |
b57aee66 | 526 | call_rcu_unlock(&crdp->mtx); |
7106ddf8 PM |
527 | wake_call_rcu_thread(crdp); |
528 | while ((crdp->flags & URCU_CALL_RCU_STOPPED) == 0) | |
529 | poll(NULL, 0, 1); | |
530 | } | |
531 | if (&crdp->cbs.head != _CMM_LOAD_SHARED(crdp->cbs.tail)) { | |
532 | while ((cbs = _CMM_LOAD_SHARED(crdp->cbs.head)) == NULL) | |
533 | poll(NULL, 0, 1); | |
534 | _CMM_STORE_SHARED(crdp->cbs.head, NULL); | |
535 | cbs_tail = (struct cds_wfq_node **) | |
536 | uatomic_xchg(&crdp->cbs.tail, &crdp->cbs.head); | |
537 | cbs_endprev = (struct cds_wfq_node **) | |
538 | uatomic_xchg(&default_call_rcu_data, cbs_tail); | |
539 | *cbs_endprev = cbs; | |
540 | uatomic_add(&default_call_rcu_data->qlen, | |
541 | uatomic_read(&crdp->qlen)); | |
542 | cds_list_del(&crdp->list); | |
543 | free(crdp); | |
544 | } | |
545 | } | |
546 | ||
547 | /* | |
548 | * Clean up all the per-CPU call_rcu threads. | |
549 | */ | |
550 | void free_all_cpu_call_rcu_data(void) | |
551 | { | |
552 | int cpu; | |
553 | struct call_rcu_data *crdp; | |
554 | ||
555 | if (maxcpus <= 0) | |
556 | return; | |
557 | for (cpu = 0; cpu < maxcpus; cpu++) { | |
558 | crdp = get_cpu_call_rcu_data(cpu); | |
559 | if (crdp == NULL) | |
560 | continue; | |
561 | set_cpu_call_rcu_data(cpu, NULL); | |
562 | call_rcu_data_free(crdp); | |
563 | } | |
564 | } | |
565 | ||
81ad2e19 PM |
566 | /* |
567 | * Acquire the call_rcu_mutex in order to ensure that the child sees | |
568 | * all of the call_rcu() data structures in a consistent state. | |
569 | * Suitable for pthread_atfork() and friends. | |
570 | */ | |
571 | void call_rcu_before_fork(void) | |
572 | { | |
573 | call_rcu_lock(&call_rcu_mutex); | |
574 | } | |
575 | ||
576 | /* | |
577 | * Clean up call_rcu data structures in the parent of a successful fork() | |
578 | * that is not followed by exec() in the child. Suitable for | |
579 | * pthread_atfork() and friends. | |
580 | */ | |
581 | void call_rcu_after_fork_parent(void) | |
582 | { | |
583 | call_rcu_unlock(&call_rcu_mutex); | |
584 | } | |
585 | ||
7106ddf8 PM |
586 | /* |
587 | * Clean up call_rcu data structures in the child of a successful fork() | |
81ad2e19 PM |
588 | * that is not followed by exec(). Suitable for pthread_atfork() and |
589 | * friends. | |
7106ddf8 PM |
590 | */ |
591 | void call_rcu_after_fork_child(void) | |
592 | { | |
593 | struct call_rcu_data *crdp; | |
594 | ||
81ad2e19 PM |
595 | /* Release the mutex. */ |
596 | call_rcu_unlock(&call_rcu_mutex); | |
597 | ||
7106ddf8 PM |
598 | /* |
599 | * Allocate a new default call_rcu_data structure in order | |
600 | * to get a working call_rcu thread to go with it. | |
601 | */ | |
602 | default_call_rcu_data = NULL; | |
603 | (void)get_default_call_rcu_data(); | |
604 | ||
605 | /* Dispose of all of the rest of the call_rcu_data structures. */ | |
606 | while (call_rcu_data_list.next != call_rcu_data_list.prev) { | |
607 | crdp = cds_list_entry(call_rcu_data_list.prev, | |
608 | struct call_rcu_data, list); | |
609 | if (crdp == default_call_rcu_data) | |
610 | crdp = cds_list_entry(crdp->list.prev, | |
611 | struct call_rcu_data, list); | |
612 | crdp->flags = URCU_CALL_RCU_STOPPED; | |
613 | call_rcu_data_free(crdp); | |
b57aee66 PM |
614 | } |
615 | } |